Retrogradation is a kinetic reaction/process in which water separates from the gelatinized starch and the gelatinized starch molecules progressively reassociate until a fine microcrystalline precipitate forms. This phenomenon is also known as synersis. The retrogradation process may be accelerated by cooling a hot or warm starch paste. The process of retrogradation takes place even in the solid state; for example, in the staling of cake or bread or cooked pasta. In fact, the texture of cooked pasta becomes grainy and mealy after refrigeration for more than 24 hours.
Retrogradation in a paste is determined by measuring the Brookfield viscosity of a paste immediately after pasting and then re-measuring the viscosity at room temperature after 3 and 24 hours. The less the viscosity change during the 3 hour and 24 hour intervals, the smaller is the degree of retrogradation.
Retrogradation in a dried pasta product is a subjective determination made by experienced panelists that sample pasta products and record their observations regarding the integrity of the texture of the product. Retrogradation can also be measured objectively with a differential scanning calorimeter.
Pasta is a starch containing product that is formed from an alimentary paste. Such pastes are generally made from coarse hard flours obtained from hard wheat such as the middlings of durum wheat. Durum wheat is often referred to as semolina flour or semolina. Semolina comprises a major portion of the flour in alimentary pastes because it is highly glutinous and provides a self-supporting pasta. A paste is formed by mixing the semolina with water and optionally additional ingredients prior to extruding the pasta into a shaped product. Shaped products made therefrom will substantially maintain their original form after subsequent processing such as cooking.
U.S. Pat. No. 4,491,483 to Dudacek et al discloses the preparation of a hot water dispersible granular starch product. The product includes the starch and at least 0.35% by weight of a surfactant containing a fatty acid moiety. Representative surfactants are glycerol monostearate, sodium stearoyl lactylate, D-glucose 3-stearate, methyl alpha-D-glucoside 6-stearate, sucrose monostearate, sorbitan tetrastearate, stearoyl-2-lactylate, sodium stearoyl fumarate etc. The product is identified as having a reduced tendency for retrogradation.
U.S. Pat. No. 4,840,808 to Lee (herein incorporated by reference) at al discloses a method for preserving color of vegetable pasta products. Color is enhanced by the addition of a cation such as magnesium, zinc, copper, calcium, and aluminum cations to the paste mixture. In addition, the patent discloses the presence of salt and glycerol monostearate to the paste mixture. Salt provides flavor. Glycerol monostearate functions as an emulsifier or lubricant or flow modifier, which reduces the viscosity of alimentary paste, making extrusion easier. It is reported that the use of glycerol monostearate will reduce the pressure within the extruder.
U.S. Pat. No. 4,529,609 (herein incorporated by reference) discloses the addition of a finely divided salt (NaCl) throughout a dough of wheat flour and water and drying the product to a moisture content of at least 15%. The salt is disclosed as allowing the use of other than semolina flour to prepare a pasta product. In addition, it interacts with the protein molecules in the dough at their polar sites which increases product flexibility. The salt is also reported to reduce the surface tension of the water which enables more complete hydration of the protein and starch granules.
U.S. Pat. No. 5,599,573 relates to preparing a cooked pasta product. The initial ingredient mix includes flour, water, acid and optionally propylene glycol alginate, spices, and glycerol monostearate. This product is prepared by mixing the flour with the acid and other ingredients. In addition, this product is produced by the cumbersome process of twice steaming acidified pasta with an intermediate water treatment. Glycerol monostearate is added to improve firmness, reduce stickiness and minimize absorption of water from a sauce component. No purpose is stated for the presence of PGA.
U.S. Pat. No. 3,332,786, issued Jul. 25, 1967 to Edlin, relates to the stabilization of starch against enzymatic degradation by the addition thereto of propylene glycol alginate. Edlin teaches the use of propylene glycol alginate to stabilize starch, including wheat starch, against degradation by amylase enzymes in an aqueous acid environment. Improvement of pasta texture is not taught and, in fact, the process of Edlin only produces a paste, not an extrudable pasta.
U.S. Pat. No. 4,517,215 relates to a process for preparing a vegetable pasta containing sodium or potassium alginate, starch and propylene glycol alginate.
U.S. Pat. No. 3,426,125, issued Aug. 19, 1947 to Steiner describes propylene glycol alginate.